<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>04_JS流程控制</title>
</head>
<body>
<script>
    //1.顺序结构
    console.log('1');
    console.log('2');
    console.log('3');

    //2.分支结构
    let uname = '张三';
    if(!uname){
        alert('请先登录！');
    }else{
        alert('欢迎'+uname+'回归！');
    }

    //3.选择分支
    let gender =30;
    switch (gender){
        case 1:
            console.log('男');
            break;
        case 2:
            console.log('女');
            break;
        default:
            console.log('未知');
    }


    //4.循环结构
    let names = ['张三','李四','王五'];
    for(var i=0;i<names.length;i++){
        console.log(names[i]);
    }
    //如果用var定义循环变量i，循环结束后再此处仍能打印出i的值
    //但如果用let定义，就会报错，变量i不存在！
    console.log(i);


//5.增强for循环
    for(let name of names){
        console.log(name);
    }


</script>

</body>
</html>